KASAN: slab-out-of-bounds Read in hci_extended_inquiry_result_evt

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7f2c5eb4 Linux 4.14.191
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=10c918fc900000
kernel config: https://syzkaller.appspot.com/x/.config?x=881f1aee9620bf9f
dashboard link: https://syzkaller.appspot.com/bug?extid=96761b8d6446f0a881b0
compiler: gcc (GCC) 10.1.0-syz 20200507

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+96761b...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:372 [inline]
BUG: KASAN: slab-out-of-bounds in bacpy include/net/bluetooth/bluetooth.h:233 [inline]
BUG: KASAN: slab-out-of-bounds in hci_extended_inquiry_result_evt.isra.0+0x17b/0x4f0 net/bluetooth/hci_event.c:3841
Read of size 6 at addr ffff8880630f3248 by task kworker/u5:0/17560

CPU: 1 PID: 17560 Comm: kworker/u5:0 Not tainted 4.14.191-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: hci4 hci_rx_work
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x1b2/0x283 lib/dump_stack.c:58
print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
kasan_report_error.cold+0x8a/0x194 mm/kasan/report.c:351
kasan_report+0x6f/0x7b mm/kasan/report.c:409
memcpy+0x20/0x50 mm/kasan/kasan.c:302
memcpy include/linux/string.h:372 [inline]
bacpy include/net/bluetooth/bluetooth.h:233 [inline]
hci_extended_inquiry_result_evt.isra.0+0x17b/0x4f0 net/bluetooth/hci_event.c:3841
hci_event_packet+0xcfb/0x7c7a net/bluetooth/hci_event.c:5376
hci_rx_work+0x3e6/0x970 net/bluetooth/hci_core.c:4244
process_one_work+0x793/0x14a0 kernel/workqueue.c:2116
worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Allocated by task 21119:
save_stack mm/kasan/kasan.c:447 [inline]
set_track mm/kasan/kasan.c:459 [inline]
kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
__do_kmalloc_node mm/slab.c:3682 [inline]
__kmalloc_node_track_caller+0x4c/0x70 mm/slab.c:3696
__kmalloc_reserve net/core/skbuff.c:137 [inline]
__alloc_skb+0x96/0x510 net/core/skbuff.c:205
alloc_skb include/linux/skbuff.h:980 [inline]
bt_skb_alloc include/net/bluetooth/bluetooth.h:336 [inline]
vhci_get_user drivers/bluetooth/hci_vhci.c:180 [inline]
vhci_write+0xb1/0x420 drivers/bluetooth/hci_vhci.c:299
call_write_iter include/linux/fs.h:1778 [inline]
new_sync_write fs/read_write.c:469 [inline]
__vfs_write+0x44c/0x630 fs/read_write.c:482
vfs_write+0x17f/0x4d0 fs/read_write.c:544
SYSC_write fs/read_write.c:590 [inline]
SyS_write+0xf2/0x210 fs/read_write.c:582
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 20116:
save_stack mm/kasan/kasan.c:447 [inline]
set_track mm/kasan/kasan.c:459 [inline]
kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
__cache_free mm/slab.c:3496 [inline]
kfree+0xc9/0x250 mm/slab.c:3815
skb_free_head net/core/skbuff.c:554 [inline]
skb_release_data+0x5f6/0x820 net/core/skbuff.c:574
skb_release_all net/core/skbuff.c:631 [inline]
__kfree_skb net/core/skbuff.c:645 [inline]
kfree_skb+0xe7/0x390 net/core/skbuff.c:663
skb_queue_purge+0x14/0x30 net/core/skbuff.c:2855
hci_sock_release+0x1bc/0x410 net/bluetooth/hci_sock.c:875
__sock_release+0xcd/0x2b0 net/socket.c:602
sock_close+0x15/0x20 net/socket.c:1139
__fput+0x25f/0x7a0 fs/file_table.c:210
task_work_run+0x11f/0x190 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:191 [inline]
exit_to_usermode_loop+0x1ad/0x200 arch/x86/entry/common.c:164
prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
entry_SYSCALL_64_after_hwframe+0x46/0xbb

The buggy address belongs to the object at ffff8880630f3040
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 8 bytes to the right of
512-byte region [ffff8880630f3040, ffff8880630f3240)
The buggy address belongs to the page:
page:ffffea00018c3cc0 count:1 mapcount:0 mapping:ffff8880630f3040 index:0xffff8880630f32c0
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff8880630f3040 ffff8880630f32c0 0000000100000005
raw: ffffea00022bee60 ffffea0002215ce0 ffff88812fe52940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8880630f3100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff8880630f3180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8880630f3200: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
^
ffff8880630f3280: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
ffff8880630f3300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 7f2c5eb4 Linux 4.14.191
git tree: linux-4.14.y

console output: https://syzkaller.appspot.com/x/log.txt?x=152f0832900000

kernel config: https://syzkaller.appspot.com/x/.config?x=881f1aee9620bf9f
dashboard link: https://syzkaller.appspot.com/bug?extid=96761b8d6446f0a881b0
compiler: gcc (GCC) 10.1.0-syz 20200507

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1572810c900000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14b8a0fc900000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+96761b...@syzkaller.appspotmail.com

audit: type=1400 audit(1596368109.832:8): avc: denied { execmem } for pid=6354 comm="syz-executor705" scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=process permissive=1
IPVS: ftp: loaded support on port[0] = 21

==================================================================
BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:372 [inline]
BUG: KASAN: slab-out-of-bounds in bacpy include/net/bluetooth/bluetooth.h:233 [inline]
BUG: KASAN: slab-out-of-bounds in hci_extended_inquiry_result_evt.isra.0+0x17b/0x4f0 net/bluetooth/hci_event.c:3841

Read of size 6 at addr ffff888091817248 by task kworker/u5:0/1202

CPU: 0 PID: 1202 Comm: kworker/u5:0 Not tainted 4.14.191-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

Workqueue: hci0 hci_rx_work

Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x1b2/0x283 lib/dump_stack.c:58
print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
kasan_report_error.cold+0x8a/0x194 mm/kasan/report.c:351
kasan_report+0x6f/0x7b mm/kasan/report.c:409
memcpy+0x20/0x50 mm/kasan/kasan.c:302
memcpy include/linux/string.h:372 [inline]
bacpy include/net/bluetooth/bluetooth.h:233 [inline]
hci_extended_inquiry_result_evt.isra.0+0x17b/0x4f0 net/bluetooth/hci_event.c:3841
hci_event_packet+0xcfb/0x7c7a net/bluetooth/hci_event.c:5376
hci_rx_work+0x3e6/0x970 net/bluetooth/hci_core.c:4244
process_one_work+0x793/0x14a0 kernel/workqueue.c:2116
worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Allocated by task 6355:

save_stack mm/kasan/kasan.c:447 [inline]
set_track mm/kasan/kasan.c:459 [inline]
kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
__do_kmalloc_node mm/slab.c:3682 [inline]
__kmalloc_node_track_caller+0x4c/0x70 mm/slab.c:3696
__kmalloc_reserve net/core/skbuff.c:137 [inline]
__alloc_skb+0x96/0x510 net/core/skbuff.c:205
alloc_skb include/linux/skbuff.h:980 [inline]
bt_skb_alloc include/net/bluetooth/bluetooth.h:336 [inline]
vhci_get_user drivers/bluetooth/hci_vhci.c:180 [inline]
vhci_write+0xb1/0x420 drivers/bluetooth/hci_vhci.c:299
call_write_iter include/linux/fs.h:1778 [inline]
new_sync_write fs/read_write.c:469 [inline]
__vfs_write+0x44c/0x630 fs/read_write.c:482
vfs_write+0x17f/0x4d0 fs/read_write.c:544
SYSC_write fs/read_write.c:590 [inline]
SyS_write+0xf2/0x210 fs/read_write.c:582
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 4429:

save_stack mm/kasan/kasan.c:447 [inline]
set_track mm/kasan/kasan.c:459 [inline]
kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
__cache_free mm/slab.c:3496 [inline]
kfree+0xc9/0x250 mm/slab.c:3815

kernfs_fop_release+0x10e/0x180 fs/kernfs/file.c:783

__fput+0x25f/0x7a0 fs/file_table.c:210
task_work_run+0x11f/0x190 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:191 [inline]
exit_to_usermode_loop+0x1ad/0x200 arch/x86/entry/common.c:164
prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
entry_SYSCALL_64_after_hwframe+0x46/0xbb

The buggy address belongs to the object at ffff888091817040

which belongs to the cache kmalloc-512 of size 512
The buggy address is located 8 bytes to the right of

512-byte region [ffff888091817040, ffff888091817240)

The buggy address belongs to the page:

page:ffffea00024605c0 count:1 mapcount:0 mapping:ffff888091817040 index:0x0
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff888091817040 0000000000000000 0000000100000006
raw: ffffea000248eae0 ffffea0002673060 ffff88812fe52940 0000000000000000

page dumped because: kasan: bad access detected

Memory state around the buggy address:

ffff888091817100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff888091817180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888091817200: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
^
ffff888091817280: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
ffff888091817300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

[syzbot]

syzbot suspects this issue was fixed by commit:

commit d91299b8382b129156708708d69876e753b9ade6
Author: Peilin Ye <yepei...@gmail.com>
Date: Fri Jul 10 16:09:15 2020 +0000

Bluetooth: Fix slab-out-of-bounds read in hci_extended_inquiry_result_evt()

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=16afe029900000
start commit: 7f2c5eb4 Linux 4.14.191
git tree: linux-4.14.y

kernel config: https://syzkaller.appspot.com/x/.config?x=881f1aee9620bf9f
dashboard link: https://syzkaller.appspot.com/bug?extid=96761b8d6446f0a881b0

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1572810c900000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14b8a0fc900000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: Bluetooth: Fix slab-out-of-bounds read in hci_extended_inquiry_result_evt()

For information about bisection process see: https://goo.gl/tpsmEJ#bisection